Scapular movements are abduction and adduction in the coronal plane, forward titling and rerotilting in the sagittal plane, internal and external rotation in the axial plane, scapular elevation and depression, scapular retraction and protraction.  Scapular dyskinesis means abnormal movements or positioning of the scapula.  The commonest is the scapular protraction.  In an excessively protracted scapula the chance for the contact between the acromion and the supraspinatus tendon is high and thus the impingement symptoms.  This is why scapular retraction exercises are helpful in impingement syndrome of the shoulder.  Abnormally places scapula does not provide a stable platform for shoulder movements (all shoulder muscles start o inser to scapula) and thus shoulder pain due to shoulder muscle fatigue and weakness can be traced to scapular dyskinesis